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Old 09-23-2020, 02:25 PM   #1
maxslo
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Default Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Hi, I have a M17x R4 board here that doesn't power on, the first thing i checked was power button and BIOS voltages.
Power button was around 19v :/ and bios was at 0v, so not even close here.

After poking around on the board with the help of schematics (In attachement)
I've found out that the PQ27 and PQ28 (3.3v and 5v high side mosfets) werent outputting anything, both gates were at 0V.
Further digging showed that both +5VALWP and +3VALWP had 13ohm resistance to ground only.

I've removed PL10 and PL11, PC58 and PC63, desoldered all of the PJP3-PJP6 jumpers.
Still showing 13 ohms when i check positive pad of PC58 or PC63 to GND.

From what i understood from schematics the only way to have path to ground is via the PU4 (PSU Controller)... when i removed it it showed that there is open line on same points as was 13 ohms before. I've checked the VO1 and VO2 (PINs 24/7) out of circuit and they both have resistance in 100+ kOhms, putting the chip back in the board and the resistance drops to 2kOhms, plugging in ac and BAM, back to 13ohm...

Here are the readings on PU4 when it's in circuit, shich all seem ok except the ones that are 0, but shouldn't be.
EN is 3.13V
REF, TONSEL, SKIPSEL are all 2V
VREG3 is 3.3V
VREG5 is 5V
BOOT1 and BOOT2 are 4.55V both
VIN is 19.5V
everything else is 0V


What am i missing here?

Any help appreciated.
Attached Files
File Type: pdf Dell Alienware M17x R4.pdf (2.15 MB, 18 views)
File Type: pdf DS8205LM-05.pdf (403.1 KB, 4 views)

Last edited by maxslo; 09-23-2020 at 02:30 PM.. Reason: Added PU4 Datasheet
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Old 09-23-2020, 02:34 PM   #2
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

3.3, 5 and bios voltages comes only after power botton is pressed

edit: u36 (near kbc) u have 3.3 volt on pin 8 ? is firmware of ec ok ?

Last edited by dellxps15; 09-23-2020 at 02:46 PM..
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Old 09-23-2020, 03:25 PM   #3
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Hi, i haven't thought about that, but power button should still have 3.3v and not 19v?
The thing is that the PU4 is also heating up when the board is powered off.

BIOS and EC were reflashed with a good working one (atleast others said that they worked for them).
Look at that, U36 does have 3.3V on pin 8. How did i miss that :S

I've added the original dumps and A11 that i've flashed to the attachments.
Both chips were reprogrammed out of circuit.
Attached Files
File Type: zip Original.zip (3.50 MB, 3 views)
File Type: zip A11.zip (3.11 MB, 2 views)

Last edited by maxslo; 09-23-2020 at 03:31 PM.. Reason: Added attachment.
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Old 09-23-2020, 04:59 PM   #4
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Quote:
but power button should still have 3.3v and not 19v?
Correct!

Quote:
From what i understood from schematics the only way to have path to ground is via the PU4 (PSU Controller)
You can also have a path to ground through PQ29 and PQ30 if they are faulty (shorted or leaky). Check continuity across them to check if are still good. Measure out of circuit if result in inconclusive.

Quote:
Look at that, U36 does have 3.3V on pin 8. How did i miss that :S
Depends which of the 2 BIOS chip you measured initially. EC BIOS (U36) is powered by +3VALW_EC (renamed from +3VLP) which is always present while main BIOS (U48) is powered by +3V_PCH which will come up after pressing power button (provided it meets required sequence)

Last edited by Spider1211; 09-23-2020 at 05:26 PM..
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Old 09-23-2020, 11:51 PM   #5
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

that 19V on power butoon is really weird. find source of it.
measure D26
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Old 09-24-2020, 12:54 AM   #6
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Quote:
Originally Posted by Spider1211 View Post
Correct!


You can also have a path to ground through PQ29 and PQ30 if they are faulty (shorted or leaky). Check continuity across them to check if are still good. Measure out of circuit if result in inconclusive.


Depends which of the 2 BIOS chip you measured initially. EC BIOS (U36) is powered by +3VALW_EC (renamed from +3VLP) which is always present while main BIOS (U48) is powered by +3V_PCH which will come up after pressing power button (provided it meets required sequence)
PQ29 and PQ30 were removed, the 15ohm is on the other side of PL10 / PL11 pads.

Yeah i didn't realise that, i've measured the main BIOS chip not the EC one initially.

Quote:
Originally Posted by ktmmotocross View Post
that 19V on power butoon is really weird. find source of it.
measure D26
The D26 is 1.8MOhms forwards and OL in reverse.
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Old 09-24-2020, 02:04 AM   #7
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Did you replace PU4 or just soldered the old one back? If the latter, then try replacing PU4.
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Old 09-24-2020, 02:12 AM   #8
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

19volt on power botton is ok. after u press power botton ig toes to 3.3

remove pjp3 or pjp4 , pjp5, pjp6. check if pu4 is ok or need replacement.

pjp point all near pl10 and pl11. clean well with flux and desolder wick.

Last edited by dellxps15; 09-24-2020 at 02:23 AM..
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Old 09-24-2020, 02:21 AM   #9
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

OP already did that in post #1 (3rd paragraph). I have never seen 19V on power button, have you?
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Old 09-24-2020, 02:24 AM   #10
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

i was editing. nope never seen it. on schematic it get 3valways. i have that board that give 7 or 8 beep... no cpu and it has 19 volt on powerbotton that goes to 3 after u press power botton
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Old 09-24-2020, 02:26 AM   #11
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Curious to know which board is that. Do you have a model number?
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Old 09-24-2020, 02:29 AM   #12
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

ls-6609p for m17x r4
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Old 09-24-2020, 02:51 AM   #13
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

I've got a M17x R3 board that powers on but gives 7 beeps, i've scavanged the PU4 from there since based on the schematics it should be the same chip even though i can't get datasheet for it.
After replacing it, nothing changes, everything is exactly as before.

I also have a complete working M17x R3 that i can probe the power button on in off state to confirm what voltage is there.
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Old 09-24-2020, 02:53 AM   #14
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

when 19 volt on power botton could be a bad kb9300f... lets wait what volt he read on that working m17x and then we can make progression.

also rememer to remove pjp as posted
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Old 09-24-2020, 03:03 AM   #15
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Ok, i'll do that.

The PJP3-6 were all removed already, there was no change.
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Old 09-24-2020, 03:26 AM   #16
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

On a good R3 board, the power button has 3.1V when in off state.

There is always 5V and 3.3V (not only after it's powered on) on the points where i don't have voltage on the R4 board.

Funny thing is that when it's in off state, it has 15ohm resistance to ground on that same points, so i guess this is not the problem??

I'll put the board back together and double check my measurements on the faulty r4 board.

Edit: on working laptop the resistance to ground measured on PL11 was actually 0ohm when the laptop was turned on o.O how can it be dead shorted to ground.

Last edited by maxslo; 09-24-2020 at 03:32 AM..
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Old 09-24-2020, 03:36 AM   #17
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Quote:
Originally Posted by dellxps15 View Post
when 19 volt on power botton could be a bad kb9300f... lets wait what volt he read on that working m17x and then we can make progression.

also rememer to remove pjp as posted
If it comes down to KB930QF, since it's the same chip on the R3, can i just swap it around, or does it have to be programmed?
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Old 09-24-2020, 04:18 AM   #18
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

keep in mind that this r4 i have here has 19 volt on pwbtn too , but it beep as no cpu even if cpu get hot.

without pressing power botton,
on jbtn pin 1 that should be 5vs is 0 volt
pin 2 is 19 volt.
d26 has 19 volt on pin 2 and 3, and has 3.3 on pin 1 (dont look at scheamtic for pinout)
L43 has 3.3 volt
r262 has 3.36 volt both side

pu3 pin 1 is 5 volt
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Old 09-24-2020, 04:36 AM   #19
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

page 53, pr32 and pr33 are the cause of 19volt on power botton.

edit their valure are ok..... 100k and 22k...

pq7 has 19 volt

im thinking that on m17x r4 19volt is normal...

edit2 : cant remember well 100% as long time passed, but i had a m17x r4 fully working and i think i compared that 19v to it...and the fully working one has that volts too, but not sure 100%

Last edited by dellxps15; 09-24-2020 at 04:49 AM..
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Old 09-24-2020, 04:54 AM   #20
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Default Re: Alienware M17x R4 no power, low resistance 5v/3.3v to GND

Quote:
Originally Posted by dellxps15 View Post
keep in mind that this r4 i have here has 19 volt on pwbtn too , but it beep as no cpu even if cpu get hot.

without pressing power botton,
on jbtn pin 1 that should be 5vs is 0 volt
pin 2 is 19 volt.
d26 has 19 volt on pin 2 and 3, and has 3.3 on pin 1 (dont look at scheamtic for pinout)
L43 has 3.3 volt
r262 has 3.36 volt both side

pu3 pin 1 is 5 volt
Everything is as you have, except 19V voltage is a bit lower at 18-18.5V
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